Add simple vector extension test to CI

ci-tests/test-spike

@@ -26,6 +26,7 @@ riscv64-linux-gnu-gcc -static -O2 -o hello $CI/hello.c
 riscv64-linux-gnu-gcc -static -O2 -o dummy-slliuw $CI/dummy-slliuw.c
 riscv64-linux-gnu-gcc -static -O2 -o customcsr $CI/customcsr.c
 riscv64-linux-gnu-gcc -static -O2 -o atomics $CI/atomics.c
+riscv64-linux-gnu-gcc -static -O2 -march=rv64gcv -o vector-sum $CI/vector-sum.c
 
 # run snippy-based tests
 wget https://github.com/syntacore/snippy/releases/download/snippy-2.1/snippy-x86_64-linux.tar.xz
@@ -45,6 +46,7 @@ g++ -std=c++2a -I$INSTALL/include -L$INSTALL/lib $CI/testlib.cc -lriscv -o /dev/
 
 # run tests
 time $INSTALL/bin/spike --isa=rv64gc $BUILD/pk/pk hello | grep "Hello, world!  Pi is approximately 3.141588."
+time $INSTALL/bin/spike --isa=rv64gcv $BUILD/pk/pk vector-sum | grep "The sum of the first 1000 positive integers is 500500."
 $INSTALL/bin/spike --log-commits --isa=rv64gc $BUILD/pk/pk atomics 2> /dev/null | grep "First atomic counter is 1000, second is 100"
 LD_LIBRARY_PATH=$INSTALL/lib ./test-libriscv $BUILD/pk/pk hello | grep "Hello, world!  Pi is approximately 3.141588."
 LD_LIBRARY_PATH=$INSTALL/lib ./test-customext $BUILD/pk/pk dummy-slliuw | grep "Executed successfully"

ci-tests/vector-sum.c

@@ -0,0 +1,27 @@
+#include <stdio.h>
+#include <string.h>
+#include <riscv_vector.h>
+
+int main()
+{
+  const size_t N = 1001;
+  volatile int a[N];
+  int* b = (int*)a;
+
+  for (size_t i = 0; i < N; i++)
+    a[i] = i;
+
+  vint32m8_t vsum = __riscv_vmv_v_x_i32m8(0, -1);
+  for (size_t i = 0; i < N; ) {
+    size_t vl = __riscv_vsetvl_e32m8(N - i);
+    vint32m8_t v = __riscv_vle32_v_i32m8(b + i, vl);
+    vsum = __riscv_vadd_vv_i32m8(vsum, v, vl);
+    i += vl;
+  }
+  vint32m1_t vzero = __riscv_vmv_v_x_i32m1(0, 1);
+  int sum = __riscv_vmv_x_s_i32m1_i32(__riscv_vredsum_vs_i32m8_i32m1(vsum, vzero, -1));
+
+  printf("The sum of the first %zu positive integers is %d.\n", N - 1, sum);
+
+  return 0;
+}